Advanced composites production for automotive, aerospace engineeringEngineering360 News Desk | March 11, 2019
New economical approaches to the manufacture of carbon fiber-reinforced polymer (CFRP) materials has been advanced by Williams Advanced Engineering.
The high strength-to-weight ratio and excellent fatigue and environmental resistance properties of CFRP make the material attractive for light-weighting vehicle and aircraft design and manufacture. However, increased proliferation of this material has been hampered by high production costs, lengthy fabrication cycles and other factors.
The 223 and Racetrak manufacturing technologies offer comparable performance to existing composites solutions at a cost that brings them within reach of mainstream applications.
The 223 method is characterized as a confidential process that integrates woven, dry, fiber reinforcement sheet with a separately prepared resin matrix, yielding 3D composite structures from a 2D form. The material is suitable for box-like geometries, such as battery containers for electric vehicles, and for structures currently assembled from many separate components, where access for fitting-out adds time and cost.
Currently an automotive body-in-white — the name for the production stage where the auto frame and chassis is assembled, but systems still need installation — typically consists of around 300 metal pressings, made with perhaps 600 different tools. Using 223, the number of pressings could be reduced to around 50, all created on a single machine to reduce the capital expenditure for tooling. A weight saving as high as 30%, relative to an equivalent aluminum structure, could be achieved.
A weight saving of around 25 to 30% could be achievable on a car’s body-in-white, compared to an equivalent aluminium alloy structure. With 223, this could be delivered in higher volumes and at a lower cost than a traditional composite solution. Where less strength is required, further cost savings could be made by specifying lower cost materials, for example glass fibers, while alternative resins can be specified to increase toughness and heat resistance.
The Racetrak process produces high-strength structural members that link two or more points, such as automotive wishbones or the link arms of aircraft landing gear. A continuous loop of carbon fiber imparts the high hoop strength, and a finished part for automotive wishbone applications could be around 40% lighter than an equivalent forged aluminum part and up to 60% lighter than steel, making it cost-competitive with a premium aluminum forging.
A core of low-cost, non-woven bulk material and a loop of unidirectional carbon fiber are encased in a protective shell made from die-cut woven fiber sheet. The reinforced material preform manufactured in the automated process is placed dry into a tool, which applies a light shaping pressure to create a removable cartridge. A vacuum is then applied in an industrial press to inject resin, which requires only 90 seconds to cure, into the heated mold. A cycle time of 120 seconds translates into the production of more than 500,000 units annually with a single press.